1. Field of the Invention
The present invention relates to a method for detecting pan size and/or position in induction heating hobs, and particularly to induction heating hobs comprising an induction coil and a plurality of magnetic field concentrators, particularly ferrite bars or the like, positioned below the induction coil. The invention also relates to an induction heating hob adapted to implement the above method.
2. Description of the Related Art
It is well known in the art of cooking appliances the need of correctly assessing the size and/or position of a cooking utensil (in the following identified generally as “pan”), particularly for alerting the user when a pan is not properly centered on the heating element and/or for automatically driving the heating element according to the size/and/or position of the pan.
Methods for pan detection in induction cooking appliances by using electrical parameters of the system (considering the system as a combination of a power converter and an induction coil linked to a pan) are well known, but while they are adequate to detect if a pan is present or not, they cannot be used to estimate pan size and/or position with meaningful precision for real life applications.
Several electrical parameters can be used for the pan detection: power factor of the load, power factor of the coil, absorption of line current, etc.
The information on pan size and/or pan position would improve the hob control by allowing more balanced power supply, especially for pans heated by multiple coils and for enhanced cooking functions, requiring water/food quantity estimation.
The basic structure of an induction heating system comprises a power converter connected to an induction coil, thus every induction heater includes a means to monitor some electrical magnitude of the power converter. This information can be also used for the basic pan detection function mentioned above (pan present or not), but it is almost useless for estimating further details about the pan, like pan size or pan position, without the use of additional sensors.